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Commit 8c1934c8 authored by Eric Paris's avatar Eric Paris
Browse files

inotify: allow users to request not to recieve events on unlinked children 

An inotify watch on a directory will send events for children even if those
children have been unlinked.  This patch add a new inotify flag IN_EXCL_UNLINK
which allows a watch to specificy they don't care about unlinked children.
This should fix performance problems seen by tasks which add a watch to
/tmp and then are overrun with events when other processes are reading and
writing to unlinked files they created in /tmp.

https://bugzilla.kernel.org/show_bug.cgi?id=16296



Requested-by: default avatarMatthias Clasen <mclasen@redhat.com>
Signed-off-by: default avatarEric Paris <eparis@redhat.com>
parent 611da04f

fs/notify/inotify/inotify_fsnotify.c

+9 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
 * General Public License for more details.

 */



#include <linux/dcache.h> /* d_unlinked */

#include <linux/fs.h> /* struct inode */

#include <linux/fsnotify_backend.h>

#include <linux/inotify.h>
@@ -157,6 +158,14 @@ static bool inotify_should_send_event(struct fsnotify_group *group, struct inode 
	mask = (mask & ~FS_EVENT_ON_CHILD);

	send = (fsn_mark->mask & mask);



	if (send && (fsn_mark->mask & FS_EXCL_UNLINK) &&

	    (data_type == FSNOTIFY_EVENT_PATH)) {

		struct path *path  = data;



		if (d_unlinked(path->dentry))

			send = false;

	}



	/* find took a reference */

	fsnotify_put_mark(fsn_mark);

fs/notify/inotify/inotify_user.c

+1 −1
Original line number Diff line number Diff line
@@ -97,7 +97,7 @@ static inline __u32 inotify_arg_to_mask(u32 arg) 
	mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD | FS_UNMOUNT);



	/* mask off the flags used to open the fd */

	mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT));

	mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK));



	return mask;

}

include/linux/fsnotify_backend.h

+1 −0
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ 
#define FS_OPEN_PERM		0x00010000	/* open event in an permission hook */

#define FS_ACCESS_PERM		0x00020000	/* access event in a permissions hook */



#define FS_EXCL_UNLINK		0x04000000	/* do not send events if object is unlinked */

#define FS_IN_ISDIR		0x40000000	/* event occurred against dir */

#define FS_IN_ONESHOT		0x80000000	/* only send event once */

include/linux/inotify.h

+1 −0
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ struct inotify_event { 
/* special flags */

#define IN_ONLYDIR		0x01000000	/* only watch the path if it is a directory */

#define IN_DONT_FOLLOW		0x02000000	/* don't follow a sym link */

#define IN_EXCL_UNLINK		0x04000000	/* exclude events on unlinked objects */

#define IN_MASK_ADD		0x20000000	/* add to the mask of an already existing watch */

#define IN_ISDIR		0x40000000	/* event occurred against dir */

#define IN_ONESHOT		0x80000000	/* only send event once */